EXPERIMENTAL INVESTIGATION OF THE WIND LOADS ON A SINGLE AND A SLUDGE-DIGESTION TANK ENSEMBLE Mircea DEGERATU*; Nicolae ALBOIU*; Georgeta BANDOC**; Amelitta LEGENDI* *Technical University of Civil Engineering Bucharest, e-mail: mircead@hidraulica.utcb.ro , nalboiu@hidraulica.utcb.ro ; legendi@xnet.ro ; **University of Bucharest, e-mail: bandoc@geo.unibuc.ro KEYWORDS: Wind tunnel, local pressure, aerodynamic force and momentum coefficients. ABSTRACT The paper describes the experimental investigation on models placed in the experimental vena of an aerodynamic boundary layer wind tunnel (BLWT) regarding the wind loads on the sludge-digestion tanks (SDT) of the waste water treatment plant serving Bucharest municipality. The purpose of the research was to determine the static load generated by the wind on two rigid models. To achieve this aim, measurements on the model of a single SDT (scale 1:100) and for an ensemble of five SDT, the technological buildings and control tower were made (scale 1:150). 1. INRODUCTION The aim of the experimental investigation was the determination on models placed in the experimental vena of the aerodynamic boundary layer wind tunnel (BLWT) of the wind loads on the sludge-digestion tanks (SDT), process steps 1 and 2 of the Bucharest municipality waste water treatment plant. For an efficient, economically and unmistakable designing this experimentally studies were considered necessary to underlain more rigorous the chosen solution and to offer the necessary data to the civil engineers. The purpose of the experimental tests was to determine the local pressure coefficients distributions on the envelope of the SDT, necessary for an optimum design of the coating elements, and the aerodynamic forces coefficients P C ( ) z y x C ,C C and and the global aerodynamic momentum coefficients ( ) y x M M C C and which act on the SDT. 2. SIMILITUDE CRITERIA Based on the Navier-Stokes and continuity (mass conservation) equation and applying the Ruark transform yields, the similitude criteria (Euler, Reynolds and Froude) and therefore the similitude criteria for models with static response, namely Eu = idem. Re = idem. and Fr=idem. finally result. Taking into account that the Froude similitude can be neglected in comparison with the Reynolds similitude and that this last assures the Euler similitude too, the only demanded condition is Re = idem. This condition is impossible to be accomplished for experimental measurements in the BLWT. Therefore, the correctness of the experimental tests was secured using the auto modeling phenomena with respect to the Reynolds criteria. 3. AERODYNAMIC BOUNDARY LAYER WIND TUNNEL. EXPERIMENTAL MODELS. MEASUREMENT EQUIPMENT Experiments were performed on rigid models of the SDT, placed in the experimental zone of the BLWT belonging to the Aerodynamics and Wind Engineering Laboratory (AWEL) of the Technical University of Civil Engineering Bucharest. ANNALS of the ORADEA UNIVERSITY. Fascicle of Management and Technological Engineering, Volume VII (XVII), 2008 205